1. Field
Embodiments of the invention relate to the field of internal combustion engine and power systems.
2. Background
At the present time, the vast majority of mobile power systems are based on spark ignition and diesel engines of conventional crankshaft and camshaft based configurations using gasoline and diesel fuel, respectively, though some such engines also operate on other fuels, such as compressed natural gas (CNG), alcohol gasoline mixtures and biofuels, to name a few alternatives enjoying some recent adaptation. Also hybrid vehicles have emerged that use a combination of battery power together with typically a spark ignition engine for backup power.
Recently there has been an awareness that carbon dioxide (CO2) appears to be a substantial cause of global warming, with the common use of fossil fuels as a source of power in both mobile and stationary power systems being the major contributor of CO2 to the atmosphere. Hence there is a strong desire to somehow reduce or eliminate the dependence on fossil fuels. There is also a strong desire to somehow store large quantities of energy far exceeding that which might be stored in batteries, and in a mobile form, to store wind power, solar power and the like to use when there is no availability of wind power, solar power (overcast or nighttime) and transport that energy to its point of use. Storing and transporting energy is an important consideration, as the best locations for generation of wind and solar power are usually well away from any existing adequate electrical distribution grid to deliver the energy to its point of use, and no practical way of storing such energy is now in use. Finally, it is recognized that the electrical distribution grid in the US is vulnerable to attack, again emphasizing the desirability of being able to more securely store and physically transport energy from the source of generation to its location of use by pipeline, rail, truck and/or other modes of distribution. The same is true for power generated by nuclear power plants.
One possibility for storage of energy at the time of its generation, and transportation to its point of use, is to use ammonia (NH3) as the energy storage medium. Ammonia is highly toxic, but is currently manufactured in substantial quantities, and is also safely transported and stored, all using well known techniques. Ammonia is particularly attractive for such use because its combustion products are only H2O (water) and N2 (nitrogen), both already in the environment in large quantities, and are the components used to generate ammonia. The combustion products are completely free of CO2, as well as soot and other hydrocarbon byproducts that result from less than totally burned fossil fuel.
The only other non-carbon based fuel currently under consideration for such use is hydrogen. Hydrogen can be generated from water, and returns to the water vapor when used as a fuel, again without generating CO2, or soot and other hydrocarbon byproducts that result from less than totally burned fossil fuel. However hydrogen presents an explosion risk over a wide range of hydrogen-air mixtures, and cannot be stored in any currently practical way to provide a reasonable heat content per unit volume of storage capacity.